Fracture Fixation Internal & External

1
Fracture Fixation Internal External
2
Fracture Types
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Influencing Healing

• Systemic Factors
• Age
• Hormones
• Functional activity
• Nerve function
• Nutrition
• Drugs (NSAID)

• Local Factors
• Energy of trauma
• Degree of bone loss
• Vascular injury
• Infection
• Type of bone fractured
• Degree of immobilization
• Pathological condition

http//www.orthoteers.co.uk/Nrujpij33lm/Orthbonef
racheal.htm
4
Stages of Fracture Healing

• Inflammation Hematoma
• Osteoprogenitor cells, Fibroblasts
• Callus Formation
• Periosteal and Endosteal
• Fibro-cartilage differentiation
• Woven Bone
• Substitution of avascular and necrotic tissue
• Haversian remodeling
• Remodeling
• Lamellar or trabecular bone
• Restoration of continuity and ossification
• Bone union
• When compression is applied via implant, these
  stages are minimized

http//www.orthoteers.co.uk/Nrujpij33lm/Orthbonef
racheal.htm http//www.ivis.org/special_books/ort
ho/chapter_03/03mast.asp?TypeIPRPLA1
5
Healing Complications

• Most often due to severe injury
• Energy dissipation to bone and soft tissue
  results in damage to blood supply
• Compartment syndrome
• Severe swelling resulting in decreased blood
  supply can cause the muscles around the fracture
  to die
• Bad osmotic pressure lets blood out instead of
  across damaged muscle
• As pressure remains high, blood cannot get to
  damaged muscle
• Neurovascular injury
• Arteries and nerves around the injury site are
  damaged
• Infection
• Imbalance of bacteria and bodys ability to cope
  with it when amount of necrotic tissue and
  contraction of bacteria are not being cleared (by
  surgeon or patient)

6
Healing Complications (Contd)

• Delayed union
• Extended healing time
• Nonunion
• Failure to heal
• Malunion
• Abnormal alignment
• Post-traumatic arthritis
• Fractures that extend into the joints can cause
  premature arthritis of a joint
• Growth abnormalities
• A fracture through an open physis, or growth
  plate, could result in premature partial or
  complete closure of the physis Part or all of a
  bone will stop growing unnaturally early

7
Treatment

• When will a cast suffice?
• Fracture is stable
• Patient preference
• No complications (Ex.-infection, burn)
• When is fixation necessary?
• Fracture is unstable
• Quick Mobilization
• Occupation
• Athletes

http//www.defence.gov.au/dpe/dhs/infocentre/publi
cations/journals/NoIDs/ADFHealthApr01/adfhealthapr
01_2_1_24-28.pdf
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Principles of fracture fixation

• Obtain and maintain alignment
• Reduction
• Transmission of compressive forces
• Minimum motion across fracture site
• Achieve stability
• Avoid tensile/ shear/torsion forces
• Across fracture site
• Prevent motion in most crucial plane

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Fixation Internal vs. External

• Internal
• Plates, screws, etc. completely within the body
• Less expensive
• Types
• Comminuted nail with interlocking screw
• Transverse or Oblique plates or screws
• External
• Pins coming through skin interconnected by
  external frame
• Has complications

http//www.defence.gov.au/dpe/dhs/infocentre/publi
cations/journals/NoIDs/ADFHealthApr01/adfhealthapr
01_2_1_24-28.pdf
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Internal Fixation
http//www.nlm.nih.gov/medlineplus/ency/imagepages
/18023.htm
11
Internal Fixation Priciples

• Rigid, anatomic fixation
• Allows an early return to function
• Reserved for those cases that cannot be reduced
  and immobilized by external means
• Open reduction of a fracture
• Good blood supply to undisturbed tissues

http//www.umm.edu/ency/article/002966.htm
12
Physiological Response to IF

• Primary healing
• Minimal extramedullary callus
• Minimal intra-medullary callus
• Sub-periosteal
• Rapid
• Related to motion
• Crosses miniature gaps
• Depends on soft tissue viability

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Stress Concentrations

• Geometric discontinuities (hole, base of
  threaded screw, corner)
• Local disturbance in stress pattern
• High stresses at site of discontinuity
• Drilling a hole reduces the bone strength by 10
  40

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Types of IF Devices

• Lag screws
• Kirschner wire
• Wire loop
• Tension band wiring
• Combination of wire loop and screw
• Combination of Kirschner and wire loop
• Plate
• Intramedullary rods and nails
• Interlocking screws

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Hemi-Arthroplasty

• In the hip, used for femoral neck fractures
• Avascular necrosis
• Fractures of the proximal humerus
• Early mobilization is facilitated

http//www.orthogastonia.com/patient_ed/html_pages
/hip/hip_hemiarthrooplasty.html
16
Bilboquet Device
http//www.maitrise-orthop.com/corpusmaitri/orthop
aedic/100_bilboquet/bilboquet_us.shtml
17
Problems in IF

• Infection
• Delayed union
• Non-union

18
External Fixation
http//www.nlm.nih.gov/medlineplus/ency/imagepages
/18021.htm
19
External Fixation

• Method of immobilizing fractures
• Employing percutaneous pins in bone attached to
• Rigid external metal
• Plastic frame
• For treatment of open and infected fractures

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Indications for EF

• Open grade III fractures
• Compound tibia fractures
• Generally from motorcycle injuries
• Gunshot wounds
• Major thermal injuries
• Open fractures associated with polytrauma
• Management of infected nonunions

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Forces in an External Fixator

• Compression
• Neutralization
• Distraction
• Angulation
• Rotation
• Translation or displacement

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Compression

• For transverse fractures
• Adds stability at nonunion site

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Neutralization

• For comminuted fracture
• Compression may lead to excessive shortening
• Used to maintain
• Length
• Alignment
• Stability

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Distraction

• For distal metaphyseal or intra-articular
  injuries
• Same principle of traction
• Distraction of fragments
• Alignment of injury

25
Angulation
A unacceptable alignment B loosening
clamps loss of distr. and compr. force C
after frames completely loosened angulation is
corrected D -
compression on distraction forces are reapplied

26
Rotation

• Exert rotational force
• Along longitudinal axis
• Release of forces first
• Can be done with repositioning pins
• Most of present frames cannot apply rotational
  forces

27
Translation or Displacement

• Volkov apparatus
• Double ring unit
• Moves one ring in parallel to other
• For translation

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Types of EF Devices

• Unilateral
• Bilateral
• Triangular
• Quadrilateral
• Semicircular Circular ring
• Ilizarov

http//www.ilizarov.org.uk/content.htm
29
Unilateral EF
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Bilateral EF
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Triangular EF
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Quadrilateral EF
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Semicircular and Circular EF
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Advantages of EF

• Easy application
• Good stability
• Excellent pain relief
• Adjustable
• Alignment, Angulation, Rotation
• Access to open wounds
• Frequent dressing change
• Monitoring of damaged tissue

35
Disadvantages of EF

• Application may cause soft tissue damage
• Lacks advantages of cyclic loadings as seen in
  casts
• Constrained in time
• Pins may drain
• Infection

36
The End
37
Granulation

• Tissue damage repair begins with growth of new
  capillaries
• Red dots are new clusters of capillaries
• Bleed easily
• Bright red tissue of a healing burn is
  granulation tissue

38
Hematoma

• Blood collection localized to an organ or tissue
• Usually clotted
• Example Contusions (bruises), black eye, blood
  collection beneath finger or toenail
• Almost always present with a fracture

http//www.healthscout.com/ency/68/677/main.html
39
Fibrocartilage

• Cartilage with a fibrous matrix and approaching
  fibrous connective tissue in structure
• Produced by fibroblasts
• Forms in areas where size of the fracture gap is
  1mm or greater
• Subsequently replaced by bone
• Mechanical properties inferior to other types of
  cartilage
• Contains
• Large amounts of collagen type I
• Reduced amounts of proteoglycans
• Collagen type II, found only in cartilage

http//www.vetmed.ufl.edu/sacs/notes/Cross-Healing
/page9.html http//wberesford.hsc.wvu.edu/histo
lch6.htm http//www.nuigalway.ie/anatomy/wilkins/
practicals/bone/html/bone_1.html http//www.bm.tec
hnion.ac.il/courses/336529/web/Cartilage/major20t
ypes.htm
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Inflammation Hematoma
http//www.ivis.org/special_books/ortho/chapter_03
/03F2.jpg
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Inflammation Hematoma

• Inflammation begins immediately after a fracture
• Initially consists of hematoma and fibrin clot
• Hemorrhage and cell death at location of fracture
  damage
• Fibroblasts, mesenchymal cells, osteoprogenitor
  cells appear next
• Formation of granulation tissue
• Ingrowth of vascular tissue
• Migration of mesenchymal cells

http//www.aans.org/education/journal/neurosurgica
l/apr01/10-4-1.pdf Simon, SR. Orthopaedic Basic
Science. Ohio American Academy of Orthopaedic
Surgeons 1994.
42
Inflammation Hematoma (Contd)

• Primary nutrient and oxygen supply provided by
  exposed cancellous bone and muscle
• Use of anti-inflammatory or cytotoxic medication
  during first week may alter the inflammatory
  response and inhibit bone healing

http//www.healthscout.com/ency/68/677/main.html
43
Callus Formation
http//www.ivis.org/special_books/ortho/chapter_03
/03mast.asp?TypeIPRPLA1
44
Callus Formation

• Begins when pain and swelling subside
• Size inversely dependent on immobilization of
  fracture
• Mesenchymal cells form cells which become
  cartilage, bone, or fibrous tissue
• Increase in vascularity
• Ends when bone fragments are immobilized by
  tissue
• Stable enough to prevent deformity
• Callus does not appear on x-ray images

• http//www.orthoteers.co.uk/Nrujpij33lm/Orthbonef
  racheal.htm
• Simon, SR. Orthopaedic Basic Science. Ohio
  American Academy of Orthopaedic Surgeons 1994.

45
Mechanical Role

• Enlarge diameter at fracture site
• Reduces mobility
• Reduces resulting strain
• Granulation Replaces Hematoma
• Granulation differentiates into
• Connective tissue
• Random orientation of collagen fibrils
• Their direction reflects the direction of tensile
  forces
• Fibrocartilage

46
Deformation of Callus

• Strength of initial reparative tissue is low
• If forces surpass the strength of callus
• Unstable fracture
• Functional load deforms fracture
• Fracture fixation is recommended

47
Woven Bone
48
Woven Bone

• Callus changes from cartilaginous tissue to woven
  bone
• Callus mineralized but internal architecture is
  not fully matured/arranged
• Osteon organization is not complete
• Connective tissues and fibrocartilage thickens
• Fracture becomes increasingly stable
• Mineralization is sensitive to strain
• Mechanically stable scaffold
• Increased strength and stiffness with increase of
  new bone joining fragments

Simon, SR. Orthopaedic Basic Science. Ohio
American Academy of Orthopaedic Surgeons 1994.
49
Bone Remodeling

• Woven bone becomes lamellar bone
• Bone union occurs at fracture gap
• Callus gradually reabsorbed by osteoclasts
• Replaced by bone
• Medullary canal reconstitutes
• Begins within 12 weeks after injury
• May last several years

http//www.glaciermedicaled.com/bone/bonesc3p2.htm
l Simon, SR. Orthopaedic Basic Science. Ohio
American Academy of Orthopaedic Surgeons 1994.
50
Mesenchymal Cells

• Source of cells for new bone production
• Derived from bone marrow cells
• Intramembranous bone formation
• Formation of bone directly from mesenchymal cells
• Cells become osteoprogenitor cells then
  osteoblasts.
• Development of Cartilage model
• Mesenchymal cells form a cartilage model of the
  bone during development

http//www.grossmont.edu/shina.alagia/lectures/144
/Bone20physiology.ppt http//www.ecmjournal.org/j
ournal/supplements/vol005supp02/pdf/vol005supp02a0
7.pdf
51
Fracture Stability

• Direction of fracture material (type of bone)
  define stability
• Definition of direction of force important
• Stable
• Fissure (Hairline) not complete break, minimal
  trauma
• Greenstick crack on outside of bend
• Unstable
• Comminuted many bone fragments
• Oblique break at an angle
• Spiral corkscrew-like crack pattern

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Lag Screw
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Lag Screw

• Stability
• Exerts inter-fragmentary compression
• Static compression
• Distal head must be engaged

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Screw Holding Force

• Increase in area of bone within screw threads
• Decrease in pilot hole size
• Increase in length of engaged threaded portion
• Area available to resist shear

55
Kirschner Wire
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Kirschner Wire (Contd)

• Rotational stability
• May be a problem
• Anchorage to tension band
• Twisting of wires on both sides
• Almost equally distributed compression

57
Tension Band
58
Tension Band (Contd)

• Dynamic compression
• When tension applied
• Compressive forces are at the fracture site
• Used
• Substitutes torn ligaments tendons
• Allows injured ligaments to heal
• When fragments too small to be screwed

http//www.wheelessonline.com/o2/1536.htm
59
Tension band Screw
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Tension Band Screw
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Plating of Vertebral Column
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Vertebral Column
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Intramedullary Pin

• Types
• Open
• Closed
• 3-point fixation
• End fixed in epiphyses

64
Intramedullary Pin (Contd)

• Stability is dependant on
• Friction / pressure between
• Deformable nail (elastic recoil)
• Endosteal surface of medullary canal
• Fracture personality

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Intramedullary Pin (Contd)

• Blood supply is from the medullary canal
• Compromised by intramedullary fixation
• More care has to be taken

66
Open Fracture

• Bone ends have penetrated through and outside
  skin
• Important features
• Polytrauma victims
• Varying soft tissue damage
• Contaminated wound
• Requires emergency treatment

67
Types of Open Fracture

• Type I Low Energy
• Puncture wound (1 cm dia. or lesser)
• Not much soft tissue contusion
• Usually simple transverse, short oblique fracture
• No crushing component
• Type II
• Laceration (more than 1 cm long )
• Not extensive soft tissue damage
• Not severe crushing component
• Type III High Energy
• Extensive damage to soft tissue
• High velocity injury or severe crushing component

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Type I
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Type II
70
Type III